Method of producing photographic contrasts



C. 15, 951 J, G, B05 TAL 2,571,670

NIET-EOD OF` PRODUCING PHOTOGRAPHIC CONTRASTS Filed Jan. 2l, 1947 2 SHEETS-SHEET l @EL 1, tg'l J, Q B05 ETAL 2,571,670

METHOD OF' PRODUCING PHOTOGRAPHIC CONTRASTS Filed Jan. 2l, 1947 2 SHEETS--SHEET 2 Patented Oct. 16, 1951 UNITED STATES PATENT OFFICE METHOD F PRODUCIN G PHOTOGRAPHIC i CONTRASTS Application JanuaryV 21, 1947, Serial No. 723,426 In the Netherlands January 21, 1946 This invention relates to a method of producing photographic contrasts, more particularly to material sensitized by means of a diazonium compound, and is of particular importance for the manufacture of copies of image and sound iilms, since it permits contrasts having diiTerent gamma values to be obtained side by side on one and the same material.

It is known that photographic material sensitized by means of light-sensitive diazonium compounds often exhibit contrasts, the graduation of which isl unsatisfactory. Thus, for example, physically developed metal images obtained by using diazonium compounds and metal compounds, e, g. a mercurous salt, reduci-ble in an aqueous medium often have a lgamma value of from 6 to 7. This is to be understood to mean the maximum value of the'gamma i. e. the maximum value of the gradient of the characteristic blackening curve. `Such a gammavalue is very suitable" for making copies of sound vrecords by means oi width variations and particularly for copying a mechanically produced sound track (cf. French patent specification 817,850). However, for copying, for example, image negatives and sound records by means of depth variations it is much too high.

It has now been found that with the aforesaid material the gamma value may depend upon the moisture content o'f the material at the moment of exposure. In a copending United States patent application Serial No. 727,310 filed February 8, 1947, exclusive rights have been claimed for a method of controlling the gradation of avphotographic contrast, in which this phenomenon is utilized. It has, however, further been found that with this kind of material the gamma value of the contrast may also'vary according as the intensity and'duration of the eX- posure vary, notably if the material has an increased moisture content. According to the present invention, the gradation of a material having a gamma value dependent upon the moisture content is confv trolled by varying the intensity and duration of the exposure, particularly with an increased moisture content of the material. The intensity of exposure is to be understood to mean the flux per cm.2 of the photo-chemically active light falling on ,the sensitized material. On varying the intensity 4and duration, that intensity and duration should be compared which, under the conditions used in regard to blackening and so on. yield the samerblackening, for instance a blackening exceeding the fog-byr0.05. i

, 4 Claims. (Cl. 95-5) A-material having va gamma value dependent upon the moisturecontent is to be understood to mean a material with which a variation ofthe moisture content, under otherwise the same con# ditions, is capable of bringing about at least'a variation of the ratio 1: 1.2 in the'gradient of that part of the characteristic blackening curve having blackenings of from 0.4 to 1.5. For comparison tests this gradient should naturally be measured at the same blackenings. Thematerial considered to have an increased moisture content if the moisture content of the part of the material being photo-chemically Iactive in the'pro'- duction'of contrasts at least exceeds theV moisture content which this part would have if the mai terial should be in equilibrium with an atmosphere having a relative vdegree of moisture of at2oc. l

It is pointed out that-apart from and in" addi# tion to the method of gamma Vcontrol according to the invention other methods of influencing the gamma remainserviceable. This is obvious, foi1 external methods such as the arrangement ofa grating closely in front of the'photographic'ma# terial (cf. French patent specification 848,531); this applies, however, also to methods in vwhich use is made of a so-called internal vgratin'gffcf; French patent specification 841,911), of a varia'- tion of the composition of developing and sensif tizing liquid, of a variation in developing time, of a variation in wavelength of the exposure?. The method according to the invention permits of being very effectively combined with the afore-ln said method consisting in varying the moisture content of the material at, the moment ofyex` posure. By combining themethod lacco'rdingffto the invention with oneV lof the last-mentioned methods, ample Variation ofthe gammav value is often obtainable whilst retaining a suicient maximum blackening and avoiding a grate struc.-` ture. v The use of the invention permits of obtaining excellent results in producing photographic con-, trasts, particularly metal images, by means of photographic material sensitized by a light-sensi-f tive diazonium compound.

This applies particularly to the production of photographic, physically developedv metal "conetrasts by means of a sensitized oxydiazonium compound and a mercurous salt.' Contrasts thus obtained are grainless, i. e. the grains are smaller than la. VIf a nlm made from: regeneratedA cellulose and impregnated' with `a lightisensitive oxydiazonium compound and a mercuroussalt, is exposed at high intensity ina moist state'and then physically developed to a neutral grey tone, a maximum gamma value of at least 4 is readily obtained. By exposing the same material at a low intensif/La gamma value of, from L5 to 2 is obtainable, whilst retaining a suflicient maximum blackening and a neutral grey tone. This renders the material very suitable, for example, for thetion, particularly at an increased moisture con.-

tent of the sensitized material. Owing to. this, it is of much importance for the manufacture of sound lm copies with which one and the same iilm band is provided with images and sound rectnd with different gradations for sound are.y desired. Photographic ma- .terial of the aforesaid kind, which consists ot a. transparent. suppone for example regenerated cellulose treatedl with` a` sensitized diazonium comand' a mercurous salt, and is physically developed, afterthe: exposure, permits of manufacturing, for examp1e soundlmcopies having an imageof low gamma, value and a sound record of highv gamma value. For this purpose the image band and the, sound record are copied, at a diilerent exposure intensity and duration. The development of the exposed copy is` preferably effected in one; operation; in spite' thereof, di-flierent,gradations are obtained for the image part and the sound part. oi'.A the copy. Copies thus obtained. are cheap and of excellent quality.

In this embodiment, in which a lm is provided with contrasts; loca-ted side by side and having ditlerent. gradations thel nlm isA preferably passed mono! continuous operation in. front'y of the exposure appa-ratusfor copying. image, and soundV the desired: exposure time being determined by a judicious; choice of the distance-the moving lm is exposed totheactiom ofthe copying light andthe desired, intensity-'being obtained, for example, by a suitable choice. of the intensity anddistance ol the' source of: light.

Elmthermore, theinvention. o n copying' a pic.- torial llnl permitsof obtaining d-iierent; gradations for succeeding seriesV of images. For example,v inv the; case ot asuccessionof` scenes, the gradationdesired for each scene may be obtained by providing for suitable exposure conditions von copying.. This is of particular importance.- for the manufacture of copies of filmreports, such as nlm, news-reels. If desired, the exposure cond-itions: may automatically be.. adjustedto thev best values2 by provid-ingv the: -lm. striptoY be copied witha control track which controls, for example by photoelectric means, the intensity and duratonof tneexposure.

Another use or thea possibility to provide= different gradations, one:A and the? same. material consists in thatdiierent. parts of, a single image are given different gradations.. On copying a portrait. or a. landscape, for, example, the; background and thefair. respectively may be given different gradations.. This use .may be of. importance for enlargement, or. .for the transmission of photog/raphcimagesC by television or the like.

v The, relation. existingZ between the exposure conditions and the gammavalue obtained depends upon variousV actors, such as the nature of the support., the, quaniziwv or the light-sensitive. com.-

pound in the support and so forth, but can be determined experimentally.

A very important factor is the moisture content of the support. As stated thinzsare even such that in, the case ot a constant exposure intensity a variation of the moisture content permits the gamma to be controlled. Consequently, for the obtainment of reproducible results, a reproducible adjustment of the moisture content is of much importance. A very reliable control of the moisture content is ensured by bringing the material in equilibrium with an atmosphere of suitable relative humidity, which may be effected byl leaving the material for a suiiiciently long time,A alm bandi of regenerated cellulose for example for 24. hours in such an atmosphere.

It is, however, not necessary that the material should be in a state of equilibrium with respect 'tor moisture content. It is suiilcient that the moisture content has the value required in regard to the desired gradation, in the zone. of the? material where the photo-chemical conversion takes piace. This permits al much quicker adjustment offthe moisture content than in the case of waitingtor the. state of equilibrium. llt.` for. example, an in.- creased moisture content is desired, the.- moisture content of the photo-chemicallyactive part of the material. is, adapted tobe adjusted to the desired. value ina very short time by treating the sensitized. material with water and by `drying it slightly or conversely by introducing dry material into a moist atmosphere., Itis to. be noted that the moisture content. of the material at the moment of exposure is vital. Ithas beentound.- that in this manner a. reliable and. reproducible con.- trol, of the gamma. value isv readily possible. The gammav value. obtained does not depend upon variations of themoisture eontentafter exposure.

Qnadjusting. the moisture content, apart from the methodby means of which thisiis carried out, the nature of the materialshould be considered. For example, if alight-sensitive dlazoniumfcompound is introduced into'gelatine, the material must be in equilibrium with. an atmospherehuuh ing a dineren-t. humidity in order to obtain the same. moisture` content. as with. regenerated cellulose. fr

To obtain good results, itis, naturally necessary that the materialwhich contains theflight-sensi.- tive compound is capable ot absorbing moisture. Excellent results are obtained by means. of regenerated cellulose. The. support1 as. a whole is not required to be capable. of absorbing moistmte, it. being suiiicient that the part of thev support containing the photo-chemically active compound is capableof absorbing water. Very suitable is, for example, a superiicially saponied cellulose, acetate or a support sensitive or not sensitive to moistureY which carries. a Water-absorbing layer, for example, gelatine. or another albumin or albuminous product containing. the light sensitive compound. vAs an. alternative, vuse may be made of a material entirely or partly consist.- ing of` polycondensation products,..such as. poly- Y amides..

The inventionwill be. explained morefully with reference to the accompanau'ng drawings., which represent characteristic curves obtained. under. diierentconditions. ofv exposure. and with dif.- ferent moisture contents.. The. curves are. inferred` trom.. the. blackening, variation oi contrasts. obtainedunder a sensitometer wedge..

Regenerated cellulose.- wasl sensitizedr by:

fatv'igevo ing it in a solution .of 0.1 n hydroxyi-l diazonium-2 methyl-6 benzene sulphonicv acid-4,. 0.025 n mercure-nitrateV and 0.'05"n nitric acid followed by conditioning at 22 C. and a relative ity `of'about 40 toV 96%, exposing the nrst portionecontaining the said moisture content to the action of light havingV a given'intensity of illumination Vto Vform a photographic contrast humidity ofilO, '75, 90 and 96% reSpeCtiVely by 5 thereon having'a given gamma value, and exleaving the material for a considerable time in posingA those'ooud' pori-,ion oontaiuing the said an atmosphere hai/ing Such a degree of humidity moisture content to the action of light havingan and temperature. Y y y intensity different from said given intensity to After that it Was eXDOSed by IneanS 0f a form a photographic contrast thereon having a PhilipsSuperhgh-DIeSSure mercury-Vapour lamp gamma value different from said given vgamma of 500 watts under a sensitometer Wedge. After 'value v y w the exposure the material Wals Washed in 'i 2 proceiss' of I producing photographic Water, developed at 22 C- in a SOllltiOn 0f 2% contrasts on'a carrier comprising a transparent metol (sulphate salt of p-methyl-aminolihenfil), cellulosic and a moisture absorbent albuminous '4% tartaric acid and 0.4% Silver nitrate,jtl1e 15 base thereover, saidY carrier having a givenfinitial time of development beingV 3 minutes fertile ma' moisture content and supporting a light-sensif 'terial conditioned to 40% and 2-minutesfor the fi'V'ofsjsfm'containing a diazonium oompounq remainder. 'Y f and a reducible mercurous salt, the lsteps coin- The characteristic curves were derivedV from Y prisiiig varying the moisture content of one poi(- the contrasts obtained, whereupon the grada- 2'0 tion of said carrier to an extent at which the retOnS 0f the Contrast/S @Ould'be detel'lnlned'r'.' I'i1e ls'ultant vmoisture content of said portion hasv a ngladatiOnS Obtained linde? dieient Condit/iene 0f value which corresponds to a state of equilibrium :exposure are stated in the table." 4 y between. said portionl and anatmosphere having The first and second column indicate the; time al relative humidity of about 40 to 96%, varying o f exposure and the Adistance of the exposure 25 the moisture content of a second portion'ofthe ,lamp from the SenSitiZed material, the following carrier to an extentat which the resultant mois# Columns Stating, under the headings 40; 75,Y A90 ture content of said second portion has a value and 96% R. H. (the `relative humidities R. H. different than the moisturecontent of said nrst at which the conditioning took place), the numportion and has a value Which corresponds to a bers of the gamma value of the contrasts obto state of equilibrium between said second portion tained.V The table states the gradientof the andA anatmosphere having a relative humidity characteristic curve atablackening I. r f of about 40 to 96%, exposingthe first portion l.. If the distance vof the exposure lamp4 should containingr the said moisture content to the acfv have a value diierent'from that indicated in the tion of light having agiven intensity of illumi-4 second column, this deviating value is stated benation to form a photographic contrast thereon tween brackets behind the gradient found.rv having a given lgamma value,l and exposingtlie Figs. l to 4 show the characteristic blackening second portion containing the said moisture concurves as found under conditioning circumtent to the action of light having an intensity stances of 40, 75, 90 and 96% of relative humidity diierent from said given intensity to form a respectively. The values stated at the abscissa 40 photographic contrast thereon having a gamma refer to relative values of log I. value diierent from said given gamma value.

Table time of exlamp disposure in tance in 40% R. H. 75% R. H. 90% R H 96% R. H.

seconds cm.

0.46 4.0 7.o (3. 2) 9.o 8.5 2.6 1.5 6.o 6.8 (5.2) 7.4 7.6 1.9 4.6 9.o 6.2 6.5 4.6 1.2 (10.8) 10.7 19.5 5.o (16.2) 5.6 3.o 30.0 28.1 5.8 3.2 2.3 (a2. 5) 9o 48.5 1s 2s 21o 59 4.o 98o 94 3.8

What we claim is: 3. In the process of producing photographic 1. In the process of producing photographic contrasts on a transparent cellulosic moisture contrasts on a transparent cellulosic moisture absorbent carrier having a given initial moisture absorbent carrier having a given initial moisture content and supporting a light-sensitive system content and supporting a light-sensitive system containing a diazonium compound and a reducicontainingadiazonium compound andareducible ble merellrollS Salt, the SteDS Comprising Varymercurous salt, the steps comprising varying ing the moisture content of a picture record portho moisture content of one portion of said oartion of said carrier to an extent at which the rier to an extent at which the resultant moisture resultant moisture Content of Said portion has content of seid portion has e value which eore velue which corresponds to a state of equilibresponds to a state of equilibrium between said rum between Said portion and an atmosphere portion and an atmosphere having a relative having a relative humidity 0f about 40 t0 96%, humidity of about 4.0 to 96%, varying the moisvarying the moisture content of a sound record ture content of a second portion of the carrier portion of the carrier to an extent at which the to `am extent ai, which the resultant moisture resultant moisture content of said sound record coni-,oni of said Second pori-,ion has a value dif` portion has a value different than the moisture ferent than the moisture content of said first content of said first portion and has a Value portion and has a value which corresponds to which corresponds ,toga State of equilibrium bea state of equilibrium between said second portween Said Second portion and en atmosphere tion and an atmosphere having a relative humidhaving o relative humidity of about 40 to 96%,

humm

msing the-picture record portion oontainin the saldrmoistnne content to the; action ofi .Baht having algiven intensity of 'illumination toA form w ih.fi'graphio` contrast.` thereon having a; vgiven gamma value,l and exposingthe.- sound record portion containing thesaid. moisturecontenty to `the..a.ction of. light having an, intensity different from said given intensity toform. aphotog'raphic contrast thereon having agamma, value rditferent trom said., given gamma value.

4. In the process of producing photographic contrasts .on a superficially saponicd cellulose carrier having a. given mitiaimoisture, content and supporting a light-sensitive system conta-ining. a dazoniumcompoundV and. a reducible` met* curous salt, the steps comprising varyingv the moisture contentoi oneportion of saidcarder to an extent. at which the resultant moisture, oon.- tent of vsaid portion has4 a value which corresponds to a state of equilibrium between. said.

portion and an atmosphere having a` relative humidity of about 40 to 96%., varying the.. mois.- ture content of a second portion of. thefcarriet .t0 an extent at which` the resultant moisture content of said second portion has a valueAA different than the moisture content. oi said rst portion and has a valueV which corresponds, to a state of equilibrium between said second portion and an atmosphere having. a, relative humidity of about 40 to 96%,. exposing the first-portion containing the said moisture content to the ac.- tion of light having4 a given intensity of illumina.- tion to formV a photographic contrast thereon having a given gamma value, and exposing the second portion containing the. saidmoisture. content to the action of light having an intensity different` from said given intensity to form a.v phocontrast thereon havingy a sommi value different from said; given gamma. value..

GOEMAN BOS; CORNELIS JOHANNES DIPPEL. HARKE JAN HOUTMAN. KLAAS JANNES KEUNING. SJOERD WIJTZES.

REFERENCES CITED The' following references are of record in the 111ey of this patent:

UNITED STATES PATENTS Name.v Date;

468,534 Charlton Jan. 5, 1892 1,396,217!!- Mees Nov: 15, 1921 1.71.0; 4552 Langguth; Apr.. 2.3,` 1929 1,861,918 Hickman June` '1,1932 1,96631-55 DHauterive July 1'1,I 1934 149933597' V,Aikintievsky Apr. 9, 193.6 2,967,690Y Alink Jan. 12, 193.7 2.10.6;868 De Boer Febr 1,l 1938 2,183,447 Dippel Dec. 12. 1939 2,196,110 Eggers Apr. 2, 1.940 2,252,906 Holst Aug. 12, 1941 2,25%356, Russell et al. v Sept. 16,1941 2,269,161 Morse Jan. 6, 1942 FOREIGN PATENTS Number Country Date 480,352 Germany Aug. 8, 1929 v3773145 vGreatBritain July 21, 1932 '135,718 France Sept. 6, 1932 8531868 France Dec. 16, 1939 OTHER REFERENCES Eder; The Inland Printer, Oct. 1925, pp. 91%93. 

1. IN THE PROCESS OF PRODUCING PHOTOGRAPHIC CONTRASTS ON A TRANSPARENT CELLULOSIC MOISTURE ABSORBENT CARRIER HAVING A GIVEN INITIAL MOISTURE CONTENT AND SUPPORTING A LIGHT-SENSITIVE SYSTEM CONTAINIG A DIAZONIUM COMPOUND AND A REDUCIBLE MERCUROUS SALT, THE STEPS COMPRISING VARYING THE MOISTURE CONTENT OF ONE PORTION OF SAID CARRIER TO AN EXTENT AT WHICH THE RESULTANT MOISTURE CONTENT OF SAID PORTION HAS A VALUE WHICH CORRESPONDS TO A STATE OF EQUILIBRIUM BETWEEN SAID PORTION AND AN ATMOSPHERE HAVING A RELATIVE HUMIDITY OF ABOUT 40 TO 96%, VARYING THE MOISTURE CONTENT OF A SECOND PORTION OF THE CARRIER TO AN EXTENT AT WHICH THE PORTION OF THE CARRIER CONTENT OF SAID SECOND PORTION HAS A VALUE DIFFERENT THAN THE MOISTURE CONTENT OF SAID FIRST PORTION AND HAS A VALUE WHICH CORRESPONDS TO A STATE OF EQUILBRIUM BETWEEN SAID SECOND PORTION AND AN ATMOSPHERE HAVING A RELATIVE HUMIDITY OF ABOUT 40 TO 96%, EXPOSING THE FIRST PORTION CONTAINING THE SAID MOISTURE CONTENT TO THE ACTION OF LIGHT HAVING A GIVEN INTENSITY OF ILLUMINATION TO FORM A PHOTOGRAPHIC CONTRAST THEREON HAVING A GIVEN GAMMA VALUE, AND EXPOSING THE SECOND PORTION CONTAINING THE SAID MOISTURE CONTENT TO THE ACTION OF LIGHT HAVING AN INTENSITY DIFFERENT FROM SAID GIVEN INTENSITY TO FORM A PHOTOGRAPHIC CONTRAST THEREON HAVING A GAMMA VALUE DIFFERENT FROM SAID GIVEN GAMMA VALUE. 